Expanded functionality stop-start fuel saving system for vocational vehicles

ABSTRACT

An engine stop-start fuel saving system for a vocational vehicle propelled by a conventional internal combustion engine and powertrain. The system uses a low storage capacity, rapid recharge, high cycle life electric energy storage device, such as an ultracapacitor. The system also includes a generator that is coupled to the engine and that is connected to recharge the electric energy storage device, as well as a motor that is powered by the energy storage device and that is coupled to the engine. The system also includes a controller that can activate the motor to restart the engine when it is stopped, and engage the generator to recharge the electric energy storage device, and that can subsequently stop the engine again when the electric energy storage device has reached a threshold charge level. The electric energy storage device also powers at least one of: integral vehicle equipment; peripheral vehicle equipment; or an electrical outlet circuit with a socket for external plugin equipment.

The present application is a divisional of U.S. patent application Ser.No. 15/998,653 filed on Aug. 16, 2018, that is a 35 USC 371 nationalstage entry of PCT/CA2016/050712 filed on Jun. 17, 2016, and whichclaims priority of U.S. provisional patent application No. 62/295,702,filed Feb. 16, 2016. These documents are hereby incorporated byreference in their entirety.

BACKGROUND

The present subject matter relates to stop-start fuel saving systems forvocational vehicles powered by a conventional internal combustion engineand powertrain.

In recent years, much effort has been expended by the automotiveindustry to develop automobiles with reduced fuel consumption and lowerexhaust emissions. A variety of technologies have been explored,including regenerative braking, hybrid electric propulsion systems, andplug-in electric propulsion systems.

One technology that has recently been adopted by a number of automobilemanufacturers is stop-start systems for vehicles having a conventionalinternal combustion engine and powertrain. Stop-start systems save fuelby shutting off the internal combustion engine when the vehicle has beenbraked to a stop, such as at a traffic light, and restarts the enginewhen the driver disengages the brake and steps on the accelerator.Stop-start systems reduce the amount of time that the engine is idlingwhile the vehicle is stopped. They therefore reduce fuel consumption,reduce exhaust emissions, reduce engine wear, and reduce noise.Stop-start systems are relatively inexpensive compared to hybrid powersystems or plug-in electric power systems.

Nevertheless, stop-start systems present a number of design challengesfor vehicles having a conventional internal combustion engine andpowertrain. For one thing, neither the battery nor the starter motor ofa conventional vehicle would be able to handle the repeated stop-startcycles as would be experienced when driving in busy city traffic. Inaddition, redesign or modification of automatic transmissions isgenerally required to ensure adequate responsiveness when a stop-startsystem restarts the internal combustion engine.

Several different types of stop-start systems have been developed bymanufacturers of consumer passenger vehicles. A summary of some of theseis provided in the report by FEV GmbH entitled “In-Market Application ofStop-start Systems in European Market” (Markus Kremer), Dec. 6, 2011.

Notwithstanding the increasing adoption of stop-start systems forautomobiles, there has so far been little deployment among vocationalvehicles such as refuse collection trucks, bucket trucks, terminaltractors, dump trucks, cement mixer trucks, urban buses, and parceldelivery trucks. This may be considered surprising because, unlike mostautomobiles, many vocational vehicles are subject to frequent stops andre-starts as part of their regular duty cycle, even when there is noheavy traffic or dense distribution of traffic lights or stop signs. Itis considered that there are at least three factors that have hinderedthe widespread adoption of stop-start systems for vocational vehicles.

For one thing, as mentioned above, developing a stop-start systeminvolves a number of design challenges, requiring extensive developmentand testing; it may well be that the relatively small markets forspecialized vocational vehicles has hindered the commitment of resourcesto develop stop-start systems for such vehicles.

Another factor pertains to the nature of the vocational vehicleindustry. Automobile manufacturers typically develop, engineer andassemble the entire vehicle. By contrast, specialized vocationalvehicles usually have several manufacturers: one or more manufacturersdesign and make the rolling chassis, which includes the frame andpowertrain, while a different manufacturer designs and builds the body,which usually includes various specialized operating features andsystems. Because of the lack of integration of the several manufacturingsteps, it may be difficult to develop new technologies that involvedesign criteria affecting both the body and the rolling chassis.

A third aspect relates to the fact that the bodies of many vocationalvehicles incorporate pieces of auxiliary equipment to execute a workingfunction, such as the bin lifting arm of a garbage truck, the elevatingboom of a bucket truck, the rotation of the drum on a cement mixertruck, and/or the bed lifter of a dump truck. Such equipment requires amechanical drive, often to power a hydraulic pump, which is generallyprovided by the engine through a power take-off interface on thetransmission or on a mechanical interface on the crankshaft of theengine. When the engine has been turned-off, the auxiliary equipmentcannot be operated.

In some cases, it has been proposed to provide a battery pack on thevehicle to provide a secondary source of energy to drive auxiliaryworking equipment such as an electric motor to operate a hydraulic pump.The battery pack must be sized in a manner to get a sufficient amount ofenergy to supply the equipment for an entire day of operation of thevehicle, during the periods when the stop-start system has turned-offthe engine. Typically, such a configuration requires a large batterythat is recharged by being plugged-in to electric mains overnight; sucha vehicle is commonly referred to as plug-in hybrid electric vehicle(PHEV).

The energy consumption of auxiliary systems on vocational vehicles canbe very significant during the course of a typical work day. As anexample, the compactor on a refuse truck requires at least 300 kJ percycle of compaction, representing over 30 kWh per day. Moreover, toachieve any given amount of usable energy, a battery should have abouttwice the capacity to provide adequate battery life.

Assuming one full charge-discharge cycle per day, a vocational vehiclewould require a battery with a minimum lifespan of at least 2500 cyclesto meet an expected vehicle life of 10 years. The lifespan of lead acidbatteries is well below this target. Although lithium-ion batteries canreach a lifespan of 2500 cycles, meeting the required energy capacitywith lithium-ion batteries is currently expensive, and the batteriesthemselves add significant weight, which of course increases fuelconsumption when the vehicle is being driven.

Vehicles with hybrid power systems generally incorporate a largelithium-ion battery pack, making it easier to incorporate a stop-startfunction with the capacity to power auxiliary equipment using the energystored in the battery pack.

The present inventors' U.S. Pat. Nos. 8,840,524 and 9,132,824 describeseveral embodiments of a stop-start system that has recently gatheredinterest among operators of heavy duty vocational vehicles such asrefuse trucks. The entire contents of U.S. Pat. Nos. 8,840,524 and9,132,824 are hereby incorporated by reference.

One of the embodiments described therein relies on an electric energystorage device which can be used to: power an electric motor that drivesa hydraulic pump to maintain hydraulic pressure in the automatictransmission when the engine has been turned off by the system; andpower a restarting motor that restarts the engine while the transmissionis in gear; and also power a motor to drive a pump to operate anauxiliary hydraulic system on the vehicle, such as the bin lifter of arefuse collection vehicle, while the engine has been turned off by thesystem.

While many stop-start systems use lithium-ion batteries, the presentinventors have recognized that in certain applications, it isadvantageous to rely on an electric energy storage device characterizedby relatively low storage capacity, and with relatively rapiddischarge-recharge times but high cycle life, compared to currentlyavailable lithium-ion batteries. Currently, Electric Double LayerCapacitors (aka EDLCs, or ultracapacitors, or super-capacitors), areavailable that meet these characteristics.

Suitable ultracapacitors selected for vocational vehicle stop-startsystems may have an energy storage capacity between about 100 to 500 Wh,which should be sufficient to operate most auxiliary equipment duringtimes when the internal combustion engine has been shut-off, and also torestart the engine. Such ultracapacitors should also have a high powercapacity to allow powering of equipment rated at something in the orderof 10 kW, and also allowing them to be recharged quickly, advantageouslyin less than one minute. Such ultracapacitors should also have alifespan in excess of about 1 million cycles to remain operational for avehicle life expectancy of 10 years. In addition, they should also becompatible with the environmental variables of the specific vocationalvehicle, including operating temperature range, corrosion resistance andvibration resistance.

The present inventors have recognized that ultracapacitors with thesecharacteristics can be very effective in stop-start systems deployed onrefuse vehicles, as one example, given their high frequency of briefstops, and short travel times between stops. Unlike a lithium-ionbattery or a nickel metal hydride battery, ultracapacitors can easily gothrough hundreds of discharge and recharge cycles in a day, while stillbeing expected to maintain full functionality throughout the life of thevehicle.

Given that ultracapacitors can sustain charge-discharge cycles in excessof one million cycles, the energy storage capacity can be reduced to aslow as the energy required to perform one operation cycle of theequipment of the vehicle plus the energy required to re-start theengine. The size of the energy storage can thus be reduced by a factorof up to at least one hundred compared to systems powered by lithium-ionbatteries. Consequently, ultracapacitors allow the stop-start system tobe smaller, lighter and less expensive than a system that relies onlithium-ion batteries.

While a stop-start system relying on ultracapacitors (or otherrelatively low energy capacity electric energy storage devices havingrelatively low storage capacity but rapid recharge times and long cyclelife characteristics) has a number of advantages in certain vocationalvehicle applications, particularly for vehicles having very frequent andshort stops where auxiliary equipment is used, such as refuse vehicles,it has now been recognized by the inventors that such a stop-startsystem can provide additional functionalities.

SUMMARY

U.S. Pat. Nos. 8,840,524 and 9,132,824 disclose charging the energystorage device either by an external power source, or by a regenerativebraking energy recovery system. However, the present inventors have nowrecognized that re-starting a vocational vehicle's engine when it isstopped to turn a generator to recharge an energy storage systemutilizing ultracapacitors has many advantages in certain applications.In particular, the combination of an ultracapacitor electrical storagedevice with recharging the electrical storage device by re-starting theengine when it is stopped to turn a generator permits much greaterflexibility in the power demand to be met by the system.

If a vocational vehicle has a stop-start system that uses a lithium-ionbattery, the capacity of the battery must be optimized for the expecteddaily demand of the auxiliary equipment it must power while the engineis off. Using a significantly larger lithium-ion battery would addweight and cost. However, if a vocational vehicle has a stop-startsystem that uses ultracapacitors that can be recharged an almostlimitless number of times by re-starting the internal combustion enginewhen it is stopped to turn a generator that recharges theultracapacitors, many more functionalities can be included withoutincreasing the storage capacity of the ultracapacitors.

The use of an electric energy storage device that uses ultracapacitorsfacilitates being able to power both integral equipment of a vocationalvehicle and peripheral equipment added to a vocational vehicle, withoutneeding to increase the energy storage capacity of the electric energystorage device. Similarly, a vocational vehicle can be employed inservice for an extended period exceeding its usual duty cycle (forexample, to accommodate an overtime shift) without needing to increasethe energy storage capacity of the electric energy storage device. Infact, such a system can be employed even on vocational vehicles that areoperated close to 24 hours per day, such as terminal tractors used toshunt trailers at cargo loading/unloading facilities.

In accordance with a first aspect of the present subject matter, thereis provided an engine stop-start fuel saving system for a vocationalvehicle propelled by a conventional internal combustion engine andpowertrain, the system comprising:

-   -   a low storage capacity, rapid recharge, high cycle life electric        energy storage device;    -   a motor that is powered by the energy storage device and that is        coupled to the engine and;    -   a generator that is coupled to the engine and that is connected        to recharge the electric energy storage device;    -   a controller that is responsive to one or more operating        conditions to activate the motor that is coupled to the engine        so as to restart the engine when it is stopped, and to engage        the generator to recharge the electric energy storage device,        and to subsequently stop the engine again when the electric        energy storage device has reached a threshold level of charge;    -   wherein the electric energy storage device also powers at least        one of:        -   integral equipment of the vehicle;        -   peripheral equipment included on the vehicle;        -   an electrical outlet circuit with a socket for external            plug-in electrical equipment.

In some examples, the electric energy storage device has a specifiedcycle life of at least one million cycles.

In some examples, the electric energy storage device has a specifiedstorage capacity of between about 100 to 500 Wh.

In some examples, the electric energy storage device can be recharged inless than 2 minutes.

In some examples, the electric energy storage device has an energydensity of 1 to 10 Wh/kg.

In some examples, the electric energy storage device has a power densityof 1 to 10 kW/kg.

In some examples, the electric energy storage device is anultracapacitor.

In some examples, the vehicle is equipped with a hydraulically activatedautomatic transmission, the system further comprising:

a) a transmission fluid pump able to supply pressurized transmissionfluid to the automatic transmission;

b) a transmission fluid pump motor that is powered by the energy storagedevice and that is mechanically connected to the transmission fluidpump;

c) the controller being responsive to one or more operating conditionsto turn off the engine when the vehicle is stopped and to use thetransmission fluid pump motor to activate the transmission fluid pump tosupply sufficient power to the transmission to maintain engagement ofthe transmission in a driving gear; and

d) the controller also being responsive to one or more operatingconditions to activate the motor that is coupled to the engine so as torestart the engine with the transmission engaged in the driving gear.

In some examples, the system comprises an auxiliary hydraulic systemmotor that is powered by the energy storage device and that ismechanically connected to a pump for an auxiliary hydraulic system ofthe vehicle, the controller also being responsive to one or moreoperating conditions to use the auxiliary hydraulic system motor toactivate the pump for the auxiliary hydraulic system to supplypressurized hydraulic fluid to the auxiliary hydraulic system.

In some examples, the controller is responsive to one or more operatingconditions to use the auxiliary hydraulic system motor to activate thepump for the auxiliary hydraulic system to supply pressurized hydraulicfluid to the auxiliary hydraulic system whether or not the engine isrunning.

In some examples, the auxiliary hydraulic system has no pump that isactivated by a mechanical connection to the engine.

In some examples, the motor that is coupled to the engine is connectedto the engine through one of a power take-off, a crankshaft and aflywheel and operable to selectively provide a starting torque to theinternal combustion engine.

In some examples, the controller activates the motor that is coupled tothe engine so as to restart the engine, and to engage the generator torecharge the electric energy storage device, when the electric energystorage device has expended about 60% of its maximum stored energy.

In some examples, after the controller has activated the motor that iscoupled to the engine so as to restart the engine and engaged thegenerator to recharge the electric energy storage device, the controllersubsequently stops the engine again when the electric energy storagedevice has reached about 55% to 70% of its maximum energy storagecapacity.

In some examples, the system comprises peripheral equipment included onthe vehicle and powered by the electric energy storage device.

In some examples, the peripheral equipment is one of a mobilemeteorological station, a mobile telecommunication antenna, a system forevaluation of road conditions, a system for evaluation oftraffic/congestion, a video surveillance system in closed circuit,and/or a data/image display.

In some examples, the system comprises an electrical outlet circuit witha socket for external plug-in electrical equipment powered by theelectric energy storage device.

In some examples, the electrical outlet circuit has an inverter todeliver AC electrical power.

In some examples, the electrical outlet circuit has a DC-DC converter todeliver DC electrical power at a different voltage from that of theelectric energy storage device.

In some examples, the system comprises integral equipment of the vehiclepowered by the electric energy storage device.

In some examples, the integral equipment comprises a motor that ismechanically connected to a pump for an auxiliary hydraulic system ofthe vehicle.

In some examples, the integral equipment comprises a DC-DC converter todeliver DC electrical power at a different voltage from that of theelectric energy storage device.

In some examples, the controller is responsive to very cold conditionsto activate the motor that is coupled to the engine so as to restart theengine when the vehicle's conventional battery and starter may be unableto do so.

DRAWINGS

In order that the claimed subject matter may be more fully understood,reference will be made to the accompanying drawings, in which:

FIG. 1 is a schematic view of a stop-start fuel saving system inaccordance with at least one embodiment;

FIG. 2 is a schematic view of a stop-start fuel saving system inaccordance with another embodiment;

FIG. 3 is a schematic view of a stop-start fuel saving system inaccordance with another embodiment;

FIG. 4 is a schematic view of a stop-start fuel saving system inaccordance with another embodiment.

FIG. 5 is a schematic view of a stop-start fuel saving system inaccordance with another embodiment.

FIG. 6 is a schematic view of a stop-start fuel saving system inaccordance with another embodiment.

FIG. 7 is a schematic view of a stop-start fuel saving system inaccordance with another embodiment.

DESCRIPTION OF VARIOUS EMBODIMENTS

It will be appreciated that, for simplicity and clarity of illustration,where considered appropriate, reference numerals may be repeated amongthe figures to indicate corresponding or analogous elements or steps.Numerous specific details are set forth in order to provide a thoroughunderstanding of the exemplary embodiments of the subject matterdescribed herein. However, it will be understood by those of ordinaryskill in the art that the embodiments described herein may be practicedwithout these specific details. In other instances, well-known methods,procedures and components have not been described in detail so as not toobscure the present subject matter. Furthermore, this description is notto be considered as limiting the scope of the subject matter in any waybut rather as illustrating the various embodiments.

As used herein, a “low storage capacity, rapid recharge, high cycle lifeelectric energy storage device” means an electric energy storage device,such as an ultracapacitor, having a cycle life of at least 100,000 to atleast one million cycles, and an energy storage capacity of less thanabout 500 Wh and being able to recharge from about 40% to about 100% ofmaximum energy storage capacity with a power supply of 5-10 kW in lessthan a few minutes.

As used herein, “integral equipment” of a vocational vehicle meanscomponents and/or systems that are conventionally included on thevehicle and powered by the engine, or the battery, such as lights,electric fans, a radio, the air conditioning compressor, the powersteering fluid pump, an air brake system, an engine coolant pump, and/ora fuel pump.

As used herein, “peripheral equipment” for a vocational vehicle meanscomponents and/or systems that are not conventionally included on thevehicle, and that provide complementary functions that may be unrelatedto the primary function of the vehicle, such as, for example on a refusetruck, an added mobile meteorological station, mobile telecommunicationantenna, system for evaluation of road conditions, system for evaluationof traffic/congestion, video surveillance system in closed circuit,and/or data/image display (e.g. for either advertisements or publicmessages).

In addition, as used herein, the wording “and/or” is intended torepresent an inclusive-or. That is, “X and/or Y” is intended to mean Xor Y or both, for example. As a further example, “X, Y, and/or Z” isintended to mean X or Y or Z or any combination thereof.

FIG. 1 schematically depicts a fuel saving system 100, which comprises astop-start system 30 installed on a powertrain 10 of a vocationalvehicle, in accordance with at least one embodiment.

The powertrain 10 may comprise an internal combustion engine (ICE) 14and a transmission 16, together forming an engine-transmission assembly18, and a driveshaft 12 connecting a wheel set 22 to the transmission16.

The engine 14 may be, for example, a diesel engine having an independentsource of energy and a rated power sufficient to move the vehicle,typically ranging from 150 kW to 325 kW. The engine 14 can also be anyother internal combustion engine such as gasoline engine, natural gasengine, propane engine, ethanol engine, biodiesel engine, biobutanolengine, dimethyl ether engine, methanol or any renewable hydrocarbonbiofuel engine.

In at least one embodiment, the stop-start system 30 may comprise anelectric energy storage device 34, at least one electricalmotor-generator 32 (powered by the electric energy storage device 34),configured to perform high frequency engine startups and an electroniccontrol module 38. Optionally, the stop-start system 30 may comprise aremote communication device 39 connected to the electronic controlmodule 38.

The electric energy storage device 34 may provide its stored energythrough an electrical connection to the electrical motor-generator 32. ADC/AC electric motor controller 36 can be used to manage the energy flowbetween the electric energy storage device 34 and the electricalmotor-generator 32. The electrical motor-generator 32 is mechanicallyconnected to the engine 14 through a mechanical interface 31. Themechanical interface 31 may be a power take-off on the transmission 16or on the engine 14, or it may be a direct mechanical connection withthe crankshaft of the engine 14. Optionally, the electricalmotor-generator 32 may be positioned between the engine 14 and thetransmission 16.

The electric energy storage device 34 may also be charged by an externalsource of electrical power through an electrical connection and/or by anelectrical braking energy recovery system and/or by the engine 14.

The electric energy storage device 34 is a low energy storage device,which may be charged and discharged frequently, without substantiallydiminishing the lifetime expectancy of the electric energy storagedevice 34. According to an exemplary embodiment, the electric energystorage device 34 has an energy storage capacity of 160 Wh, a ratedvoltage of 144V and has a duty cycle of at least one million cycles.

Advantageously, the electric energy storage device 34 is anultracapacitor.

(According to another exemplary embodiment, the electric energy storagedevice 34 has an energy storage capacity of 92 Wh, a rated voltage of 57V and has a duty cycle of two million cycles at 400 A. The electricenergy storage device 34 can be a hybrid ultracapacitor, which combinescharacteristics of lithium-ion battery (e.g. high energy storagecapacity) with characteristics of an ultracapacitor (e.g. capacity tosustain charge-discharge cycles in excess of one million cycle and smallsize/dimensions) as described herein.)

For example, the frequency of charge/discharge of the electric energystorage device 34 may be about 15 seconds to about 30 minutes. The timeof charging may be as short as about 5 seconds to about 2 or 3 minutes.The time of discharging of the electric energy storage device 34 may be5 seconds to about 30 minutes. The lifetime of such electric energystorage device 34 may be, for example, at least about 10 years, with atleast about one million cycles per lifetime. It should be noted that acycle of charge/discharge may not always be done over the full range ofoperating voltage, but may likely be done over a narrower range ofvoltage. For example, an ultracapacitor with a rated voltage of 144Vcould be recharged as soon as it reaches 140V.

The system 30 could operate with the electric energy storage device 34having any suitable energy storage capacity, if the electric energystorage device 34 can charge/discharge quickly without affecting itslifetime. In at least one embodiment, the system 30 may operate with theelectric energy storage device 34 having energy storage capacity ofabout 100 Wh to about 1 kWh. The system 30 may operate with the electricenergy storage device 34 having power capacity of about 10 kW to about30 kW without affecting significantly its lifetime.

Suitable ultracapacitors for the present application are available fromMaxwell Technologies, Inc. In one configuration, three modules eachhaving a rated voltage of 48V and a rated stored energy of 53 Wh arecombined.

As will be known to those skilled in the art, ultracapacitors can sufferfrom leakage at elevated temperatures, leading to irreversible loss ofcapacitance. Accordingly, the system advantageously includes adischarger to reduce the voltage when the vehicle will be parked for anextended period in an elevated temperature environment. (The dischargercan also be used to reduce the voltage for maintenance.) Advantageously,the system also includes a recharger powered by the vehicle'sconventional battery to restore the charge of the ultracapacitor backupto the threshold level at which the generator mechanically coupled tothe engine can recharge the ultracapacitor.

In at least one embodiment, the engine 14 may be used to recharge theenergy storage device 34. In at least one embodiment, the energy storagedevice 34 may be charged through recovering the kinetic energy ofbraking and/or using an external source of energy with photovoltaicpanels, for example. The powertrain 10 may be equipped with a brakingenergy recovery system. In particular, the motor-generator 32 may beconfigured to recover some braking energy through the transmission 16.

The stop-start system 30 may also include a communication device 39,such as, for example, an embedded computer, a data recorder, and/or aGlobal System for Mobile Communication (GSMC) module, to transferinformation collected on the vocational vehicle to an external datacollecting center. The communication device 39 may be used to monitorthe operation of the vocational vehicle (for example, fuel usage,distance traveled, GPS position, or maintenance alarms), monitor theoperation of the stop-start system (for example, total engine timesaved, engine fuel rate or operating time), or transmit real time datacollected by equipment mounted on the vehicle (for example, a mobilemeteorological station, or a traffic/congestion monitor, or videosurveillance system).

The electronic control module 38 controls the operation of thestop-start system, in response to various signals from the vehicle orfrom the operator. In at least one embodiment, the electronic controlmodule 38 shuts-off the engine 14 when the vehicle is immobile with theparking brake applied or service brake depressed or work brakeactivated. The electronic control module 38 may also monitor the gearselected in the transmission 16. Under certain conditions such as lowengine temperature, low battery voltage, anti-locking braking systemevent or low air brake pressure, the system can prevent the engine 14 toshut-off. The electronic control module 38 will automatically restartthe engine 14 from the stop mode if none of the parking brake, theservice brake, nor the work brake is activated.

The electronic control module 38 also controls the management of thestate of charge of the energy storage device 34. When the state ofcharge of the energy storage device 34 is below a low threshold level,the electronic control module 38 will operate the electricalmotor-generator 32 in generator mode to recharge the energy storagedevice 34 up to a high threshold level.

The stop-start system may be installed on vocational vehicles such asrefuse trucks or cement trucks. Such vocational vehicles may furthercomprise at least one auxiliary hydraulic system 24, which may be anyhydraulically powered piece of equipment, such as garbage compactor,hydraulic arm to lift a garbage can, rotary cement mixer or otherhydraulically powered equipment.

When the engine 14 is turned off, no power from the engine 14 isprovided to the transmission 16. Consequently, if the transmission 16 isof the automatic type, there may be a lack of hydraulic pressure and thetransmission cannot be maintained in a driving gear (for example firstgear). Instead the transmission will fall into a “neutral gear”. Afterrestarting the engine 14, the hydraulic pressure in the transmission 16would have to be built up before there would be sufficient energy forthe transmission to change from neutral to a driving gear. The timerequired for the hydraulic pressure to build up and shift to the drivinggear is typically several seconds. Consequently an operator of thevehicle will feel a lag between restarting the vehicle and when thevehicle actually starts accelerating after its transmission has selecteda driving gear. In a typical operation where the operator starts thevehicle using an electrical ignition system while the vehicle iscompletely stationary, this lag is acceptable. However, in a situationwhere the operator is used to the engine 14 idling when the vocationalvehicle is stopped, and further expects the vocational vehicle toimmediately accelerate following the operators command (for examplestepping on the gas pedal), this lag may be frustrating or evendangerous. For example, in a situation where the vocational vehicle ison an uphill incline, having a lag between the time when an operatorgives a command to accelerate and the actual time the vocational vehiclestarts accelerating can cause the vehicle to roll backwards down theincline for several seconds before being able to stop and accelerateforward.

The fuel saving system of FIG. 1 may also include an electric/hydraulictransmission assembly 40. The electric/hydraulic transmission assembly40 is used to prevent the transmission 16 from falling out of a drivinggear into a neutral gear. However, in a low duty cycle operation such asa bucket truck, the assembly is not required because the vehicle isparked with the transmission in neutral to perform the work on the site.

The electric/hydraulic transmission assembly 40 may comprise anelectrical motor 42 and a fixed displacement hydraulic pump 44. Thehydraulic pump 44 may be powered by the electrical motor 42. When theengine 14 is turned off, the fixed displacement hydraulic pump 44 mayprovide pressure through a hydraulic circuit to the transmission 16 tomaintain it in a first gear.

After starting the engine 14 using the electrical motor-generator 32,the transmission 16 will still be in a driving gear and no lag will befelt by the vehicle operator when a command to accelerate the vocationalvehicle is given. It will be appreciated that the level of power neededto maintain the transmission in gear is substantially lower than thepower needed to idle the engine 14 for even a short period of time.Therefore turning off the engine 14 and using the electric energy fromthe stop-start system 30 to engage the fixed displacement hydraulic pump44 to maintain the transmission in a driving gear can provide asignificant saving in fuel consumption.

The vocational vehicle can also have an auxiliary hydraulic assembly 20with an electric/hydraulic assembly 50. The auxiliary hydraulic assembly20 may comprise at least one auxiliary hydraulic system. The auxiliaryhydraulic systems, such as a first auxiliary hydraulic system 24 and/ora second auxiliary hydraulic system 28 shown at FIG. 1, are oftenprovided on vocational vehicles such as refuse trucks or cement trucks,on which the fuel saving system 100 may be installed.

The auxiliary hydraulic systems may be any hydraulically powered pieceof equipment, such as a garbage compactor, a hydraulic arm to lift agarbage can, a rotary cement mixer, an overhead boom for a bucket truck,a hydraulic fifth wheel boom for a yard truck or other hydraulicallypowered equipment.

As shown at FIG. 1, the first auxiliary hydraulic system 24 and thesecond auxiliary hydraulic system 28 may be connected through ahydraulic connection line 25 to an auxiliary hydraulic pump 26. When theengine 14 is on, the auxiliary hydraulic pump 26 may drive the firstauxiliary hydraulic system 24 and the second auxiliary hydraulic system28. In at least one embodiment, when the engine 14 is off (in Stopmode), in order to maintain the operation of the auxiliary hydraulicequipment of the assembly 20 an electric/hydraulic assembly 50 can beused. In at least one embodiment, the electric/hydraulic assembly 50comprises an electric DC/AC drive (inverter) 54, an electrical motor 56,and a hydraulic pump 58. In at least one embodiment, the first auxiliaryhydraulic system 24 and the second auxiliary hydraulic system 28 can befed by the auxiliary hydraulic pump 26 driven by the engine 14 and/or byan electric/hydraulic assembly 50 by using the energy stored in energystorage device 34. For example, the electric/hydraulic assembly 50 canprovide pressure through the hydraulic connection line 55 to theauxiliary equipment when the engine 14 is off. To prevent the auxiliaryhydraulic pump 26 from turning in a reverse rotation when the engine 14is shut-off and the hydraulic pump 58 is turning, a non-return valve 57is positioned on the hydraulic connection line 25. Similarly, to preventthe hydraulic pump 58 from turning in a reverse rotation when the engine14 is running, a non-return valve 59 is positioned on the hydraulicconnection line 55.

The electronic control module 38 controls the operation of theelectric/hydraulic assembly 50. The electronic control module 38activates the electrical motor 56 when there is a demand (a lever, ajoystick, or push button activated by the operator) to operate the firstauxiliary hydraulic system 24 and/or the second auxiliary hydraulicsystem 28 by providing a hydraulic fluid flow from the hydraulic pump 58equivalent to the flow provided by auxiliary hydraulic pump 26. Theelectronic control module 38 is also configured to respond to increasedhydraulic fluid flow demand from a high idle governor command byincreasing proportionally the control speed of the electrical motor 56driving the hydraulic pump 58. Driving the auxiliary hydraulic systemsof the assembly 20 using the electric/hydraulic assembly 50 can avoidlosses of energy related to continuous driving of the auxiliaryhydraulic pump 26.

Referring now to FIG. 2, shown therein is an exemplary embodiment of asystem 200 with two electric/hydraulic assemblies 51 and 70, which candrive the auxiliary hydraulic systems 24 and 28 independently and/or ondemand.

In at least one embodiment, the electric/hydraulic assemblies 51 and 70have the same components as the electric/hydraulic assembly 50 asdescribed above. When the engine 14 is turned off by the stop-startsystem, the electric/hydraulic assembly 70 can independently provide apressure to auxiliary hydraulic system 28 on request, while theelectric/hydraulic assembly 51 can independently provide a pressure toauxiliary hydraulic system 24 on request. Therefore, the auxiliarysystems of the fuel saving system 200 can be activated on demand,thereby helping to reduce energy losses generated by rotating theauxiliary hydraulic pump 26 in a by-pass valve when there is no demandfrom auxiliary hydraulic systems 24 and 28. Additionally,electric/hydraulic assemblies 51 and 70 can provide an independentvariable hydraulic flow by controlling the speed of rotation of theelectrical motor 56 and 76. This gives more flexibility on the controlof the auxiliary hydraulic systems 24 and 28 compared to the auxiliaryhydraulic pump 26, which is limited to the speed of rotation of theengine 14. Therefore, the auxiliary systems of the fuel saving system200 can be controlled more precisely, and independently from the engine14, thereby helping to reduce energy losses.

The system 200 may comprise more than two electric/hydraulic assemblies,to supply, for example, more than two auxiliary hydraulic systemsindependently.

Shown at FIG. 3 is a variation of the exemplary embodiment shown in FIG.2 wherein the auxiliary system hydraulic pump 26 is absent. Instead,hydraulic pressure and flow to the auxiliary hydraulic systems 24 and 28is provided by the electric/hydraulic assemblies 51 and/or 70 regardlessof whether the engine 14 is running or has been turned-off. An advantageof such a configuration is that it would eliminate parasitic lossesrelated to rotating the pump 26 when the hydraulic assemblies 51, 70 arenot activated. In addition, such a configuration would allow for a moreprecise and flexible control of each of the hydraulic circuits 24, 28,for example by reducing the hydraulic flow as a piston reaches eitherend of its maximum stroke to lower shock and wear of components.

Shown at FIG. 4 is an exemplary embodiment of a fuel saving system 400which comprises, in addition to the stop-start system 30 and optionalassemblies 40, 20, and 50, as described herein, a DC outlet assembly 80.

The DC outlet assembly 80 can be connected to a DC electrical system 84.A DC-DC converter 82 converts the voltage from the energy storage device34 to the voltage required to supply the DC electrical system 84. Forexample, the DC-DC converter 82 may recharge the 12V or 24V batteries ofthe vocational vehicle. In another example, the DC outlet assembly 80can be used to provide DC electrical power to an electrical motoractuating the vehicle's internal air conditioner compressor.

A vocational vehicle equipped with stop-start system 30 further enablesit to be used as a source of portable energy, similar to anengine-generator set. The nature of vocational vehicles, being oftengrouped into large fleets and usually operating in urban areas, offersthe opportunity to transform them into emergency response equipmentcapable of being deployed rapidly in the case of a major power outage.

Referring now to FIG. 5, shown therein is an exemplary embodiment of afuel saving system 500 which comprises, in addition to the stop-startsystem 30 and optional assemblies 40, 20 and 50 as described herein, anAC outlet assembly 60.

The outlet assembly 60 can be used to provide electrical power with astandard voltage of 110 Volts or 220 Volts for a tool and/or equipmentused in connection with the operation of the vocational vehicle. Theoutlet assembly 60 advantageously provides an output of 110 V at 60 Hz.The tool and/or equipment may be mounted on the vehicle or may beconnected to the vehicle externally.

Shown at FIG. 6 is an exemplary embodiment of a fuel saving system 600which comprises, in addition to the stop-start system 30 and optionalassemblies 40, 20, and 50, as described herein, an assembly 90 that maybe connected to an external electrical system of the vehicle. Theassembly 90 may include a DC/AC drive 92 to convert the DC voltage fromthe energy storage device 34 to an AC output for the external electricalsystem 94.

Another characteristic of vocational vehicles is that they usually coverstreets on a regular basis. For example, a fleet of refuse trucks orstreet sweepers will drive through all the streets on a repetitive routeand schedule, making them useful platforms to monitor a variety ofparameters in a city, such as traffic flow and parking density.

Shown at FIG. 7 is an exemplary embodiment of a fuel saving system 700which comprises, in addition to the start-stop system 30 and optionalassemblies 40, 20, and 50, as described herein, an equipment assembly 95that can drive a piece of integral equipment 98 of the vehicle. Theequipment assembly 95 may include a DC/AC electric motor controller 96to convert the DC voltage from the energy storage device 34 to an ACoutput for powering integral equipment 98 of the vehicle (for example bymeans of an electric motor 97). The integral equipment 98 may beintegral equipment that is usually powered by the engine 14. Forexample, the integral equipment may be a power steering pump, acompressor for air conditioning system, a compressor for an air brakesystem, an engine coolant pump, a fuel pump or other integral equipment(including an optional accessory) normally driven by the engine 14. Theintegral equipment assembly 95 can be installed in parallel to theoriginal equipment. The electronic control module 38 controls theoperation of the equipment assembly 95. The electronic control module 38is configured to detect a demand to operate the original equipment whenthe engine is in stop mode to drive equipment assembly 95 from theenergy stored in the energy storage device 34.

The integral equipment 98 can also replace the original equipment. Inthis case, the electronic control module 38 is configured to detect ademand to operate the original equipment independently of the enginemode to drive equipment assembly 95 from the energy stored in the energystorage device 34. It is advantageous to drive the integral equipment 98on demand with the integral equipment 98 disconnected from the rotationof the engine 14, therefore reducing energy losses.

The fuel saving system 700 could incorporate a plurality of equipmentassembly 95 to drive independently a multitude of integral equipment 98.

The fuel saving systems as described herein may be useful on workingvocational vehicles, for example, for non-typical use of the vehicles.For example, a refuse truck may serve as an emergency mobile generator.The generated energy may be also used for powering a mobilemeteorological station, a mobile telecommunication antenna, a system forevaluation of road conditions, a system for evaluation oftraffic/congestion, a video surveillance system in closed circuit, or adata/image display (e.g. advertisements or public messages).Additionally, the fuel saving system could take advantage of a remotecommunication device 39 to transfer the information collected on thevocational vehicle to an external data collecting center.

The fuel saving systems as described herein may also be adapted torestart the engine in situations where the vehicle has been left stoppedin very cold conditions, and the vehicle's conventional battery andstarter are inadequate to restart the engine.

It will be appreciated by those skilled in the art that although theabove alternative embodiments have been described in some detail manymodifications may be practiced without departing from the claimedsubject matter.

The invention claimed is:
 1. An engine stop-start fuel saving system fora vocational vehicle propelled by a conventional internal combustionengine and powertrain, the system comprising: a) a low storage capacity,rapid recharge, high cycle life electric energy storage device; b) amotor that is powered by the energy storage device and that is coupledto the engine and; c) a generator that is coupled to the engine and thatis connected to recharge the electric energy storage device; d) acontroller that is responsive to one or more operating conditions toactivate the motor that is coupled to the engine so as to restart theengine when it is stopped, and to engage the generator to recharge theelectric energy storage device, and to subsequently stop the engineagain when the electric energy storage device has reached a thresholdlevel of charge; e) wherein the controller is configured to detect ademand to operate equipment when the engine is stopped, and wherein,when said demand is detected, the controller engages the electric energystorage device to power at least one of: i) integral equipment of thevehicle; ii) peripheral equipment included on the vehicle; and iii) anelectrical outlet circuit with a socket for external plug-in electricalequipment.
 2. The system of claim 1, wherein the electric energy storagedevice has a specified cycle life of at least one million cycles.
 3. Thesystem of claim 1, wherein the electric energy storage device has aspecified storage capacity of between about 100 to 500 Wh.
 4. The systemof claim 1, wherein the electric energy storage device can be rechargedin less than 2 minutes.
 5. The system of claim 1, wherein the electricenergy storage device has an energy density of 1 to 10 Wh/kg.
 6. Thesystem of claim 1, wherein the electric energy storage device has apower density of 1 to 10 kW/kg.
 7. The system of claim 1, wherein theelectric energy storage device is an ultracapacitor.
 8. The system ofclaim 1, wherein the vehicle is equipped with a hydraulically activatedautomatic transmission, the system further comprising: a) a transmissionfluid pump able to supply pressurized transmission fluid to theautomatic transmission; b) a transmission fluid pump motor that ispowered by the energy storage device and that is mechanically connectedto the transmission fluid pump; c) the controller being responsive toone or more operating conditions to turn off the engine when the vehicleis stopped and to use the transmission fluid pump motor to activate thetransmission fluid pump to supply sufficient power to the transmissionto maintain engagement of the transmission in a driving gear; and d) thecontroller also being responsive to one or more operating conditions toactivate the motor that is coupled to the engine so as to restart theengine with the transmission engaged in the driving gear.
 9. The systemof claim 1, further comprising an auxiliary hydraulic system motor thatis powered by the energy storage device and that is mechanicallyconnected to a pump for an auxiliary hydraulic system of the vehicle,the controller also being responsive to one or more operating conditionsto use the auxiliary hydraulic system motor to activate the pump for theauxiliary hydraulic system to supply pressurized hydraulic fluid to theauxiliary hydraulic system.
 10. The system of claim 9, wherein thecontroller is responsive to one or more operating conditions to use theauxiliary hydraulic system motor to activate the pump for the auxiliaryhydraulic system to supply pressurized hydraulic fluid to the auxiliaryhydraulic system whether or not the engine is running.
 11. The system ofclaim 10, wherein the auxiliary hydraulic system has no pump that isactivated by a mechanical connection to the engine.
 12. The fuel savingsystem of claim 1, wherein the motor that is coupled to the engine isconnected to the engine through one of a power take-off, a crankshaftand a flywheel and operable to selectively provide a starting torque tothe internal combustion engine.
 13. The system of claim 1, wherein thecontroller activates the motor that is coupled to the engine so as torestart the engine, and to engage the generator to recharge the electricenergy storage device, when the electric energy storage device hasexpended about 60% of its maximum stored energy.
 14. The system of claim1, wherein after the controller has activated the motor that is coupledto the engine so as to restart the engine and engaged the generator torecharge the electric energy storage device, the controller subsequentlystops the engine again when the electric energy storage device hasreached about 55% to 70% of its maximum energy storage capacity.
 15. Thesystem of claim 1, comprising peripheral equipment included on thevehicle and powered by the electric energy storage device, wherein theperipheral equipment is one of a mobile meteorological station, a mobiletelecommunication antenna, a system for evaluation of road conditions, asystem for evaluation of traffic/congestion, a video surveillance systemin closed circuit, and/or a data/image display.
 16. The system of claim1, further comprising an electrical outlet circuit with a socket forexternal plug-in electrical equipment powered by the electric energystorage device, wherein the electrical outlet circuit has an inverter todeliver AC electrical power.
 17. The system of claim 16, wherein theelectrical outlet circuit has a DC-DC converter to deliver DC electricalpower at a different voltage from that of the electric energy storagedevice.
 18. The system of claim 1, further comprising integral equipmentof the vehicle powered by the electric energy storage device, whereinthe integral equipment comprises a motor that is mechanically connectedto a pump for an auxiliary hydraulic system of the vehicle.
 19. Thesystem of claim 18, wherein the integral equipment comprises a DC-DCconverter to deliver DC electrical power at a different voltage fromthat of the electric energy storage device.
 20. The system of claim 1,wherein the controller is responsive to activate the motor that iscoupled to the engine so as to restart the engine when the vehicle'sconventional battery and starter may be unable to do so.